Power feed for drilling machines



I E. J. KINGSBURY POWER FEED FOR DRILLING MACHINES Feb. 23, 1937.

7 Sheets-Sheet 1 Filed Sept. '7, 1934 Feb. 23, 1937. KlNGsBURY 2,071,539

POWER FEED FOR DRILLING MACHINES Filed Sept. 7, 1934 v 7 Sheets-Sheet 2Feb. 23, 1937. E. J. KINGSBURY POWER FEED FOR DRILLING MACHINES 7Sheets-Sheet 3 Filed .Sgpt. 7, 1934 Feb. 23, 1937. K|NG$BURY 2,071,539

v POWER FEED FOR DRILLING MACHINES Filed Sept. 7, 1934 7 Sheets-Sheet 4QM/21-W I Ewenfir:

'Feb. 23, 1937. E. J. Kmssumr 2,071,539

POWER FEED FOR DRILLING MACHINES Filed Sept. 7, 1934 7 sheets-sheet 5Invert/for.-

Feb. 23, 19 37. N B Y 2,071,539

POWER FEED FOR DRILLING MACHINES Filed Sept. 7, 1934 7 Sheets-Sheet s1937. E. J. KINGSBURY POWER FEED FOR DRILLING MACHINES Filed Sept. 7,1934 7 Sheets-Sheet 7 Patented Feb. 23, 1937 UNiTED STATES FA'EIENTOFFEQE 8 Claims.

This invention relates to improvements in power feeding mechanism forapparatus such as drilling machines.

One of the features of the present invention is the provision of a powerfeeding mechanism including a differentiating gearing which operateswhile the parts turn together to effect a rapid forward traversemovement, and while differentiating action is occurring to produce aslow working feed, in association with clutch means for engaging thegearing with the tool spindle for the forward movements and fordisengaging the same to permit a return movement of the spindle.

Another feature of the present invention is the provision of a powerfeeding mechanism including a continuously rotating body anddifferentiating gearing including a planet pinion carried bodily withsaid body; and sun gears, one of which is operatively connected duringthe forward feeding movement with the spindle feeding elements and theother may rotate freely in one direction for the rapid feeding movementbut is prevented from rotation in the other direction and therebyproduces a slow working feed through the action of the differentiatinggearing.

A further feature of the present invention is the provision of a powerfeeding mechanism including an element which is moved in proportion tothe feeding movement of the spindle and is provided with resilient stopswhich are adjustable for determining the limits of movement of thespindle, these stops being operative upon the control mechanism whichproduces reversal of traverse and feeding movements, and mechanism forbringing the spindle to a standstill at the completion of a cycle.

Still another feature of the present invention is the provision of apower feeding mechanism including a selective driving train forproducing rapid and slow forward movements, means for returning thespindle when the train is entirely disconnected, and anelectromagnetically operable device for producing a connection of thetrain, along with circuit means for initiating and maintaining theenergization of the electromagnetic device during the forward stroke,and interrupting the same at the limit of the forward stroke so that thedisconnection occurs and the spindle is withdrawn from the work.

With these and other features as objects in view, as will appear in thecourse of the following specification and claims, an illustrative formof practicing the invention is set out on the accompanying drawings.

In these drawings:

Fig. 1 is a front view of the mechanism head of the apparatus.

Fig. 1a. is an upright sectional view substantially on line iala of Fig.1.

Fig. 2 is a left-hand side elevation of the structure in Fig. l, with aguard cover removed, and parts broken away.

Fig. 3 is a corresponding right-hand side elevation.

Fig. 4 is a horizontal section substantially on line 4- 1 of Figs. 1, 2,and 3.

Fig. 5 is an upright section substantially on line 55 of Figs. 2, 3, and4.

Fig. 6 is a similar upright sectional view on line 6-6 of Figs. 2, 3,and 4.

Fig. 7 is a fragmentary upright section on line 1-1 of Fig. 5, on anenlarged scale.

Fig. 8 is a fragmentary horizontal section substantially on line 8--8 ofFig. 6, on an enlarged scale.

Fig. 9 is a diagram showing the various circuits and the controlsassociated therewith.

In these drawings the mechanism head of an upright drill is illustratedas having a general housing casting H with proper internal web walls forthe mounting and supporting of the parts as disclosed hereinafter, afront wall for receiving certain control structures, right-hand andleft-hand side walls with openings therein to be closed by theright-hand and left-hand cover plates RC and LC, and a rear wallincluding an inclined guideway GW upon which may move a support memberSM including upright portions MS on which is fixed a driving motor M asillustrated in my copending application Serial No. 684,063 filed August'7, 1933.

This mechanism head is supported upon a hollow column C which likewisemay receive a knee for supporting the work, etc., in the usual manner.

A driving pulley Z0 is keyed or splined on a spindle 2| which isillustrated as extending vertically downward through the head H andsupported by appropriate bearing 22 (Fig. 1a) in a quill 23 which isguided for vertical and nonrotating movement in the mechanism head H,and is provided with a rack portion 24 in mesh with the quill pinion 25.The spindle has its lower end projecting from the head H and isconnected in suitable manner to a tool such as a drill, for driving thesame in rotation.

Likewise, a power-driven vertical shaft 30 (Figs. 2 and 4) is secured toa worm 3!. This worm 3i meshes with a worm wheel 32 (Figs. 5 and 6)which forms part of a rotatable body 33 supported by a bearing 35 upon acylindrical surface 35 of a fixed shaft 35. An open end of the body 33is closed by a gear structure 3'1 rotatable relative thereto andsupported by bearings 38 engaged on a cylindrical portion 39 of theshaft 36. The body 33 supports the journal pin 40 having a bearingbushing ll and a double pinion 42 thereon: one element of the doublepinion engages with the gear teeth 33 on gear member 31, while the othermember of the double pinion engages with gear teeth 45 upon the externaloverrunning-clutch member 45 (Fig. 7), which has a cylindrical internalsurface. The overrunning-clutch structure includes a portion 46 of thefixed shaft 36 which has illustratively three notches 47 (Fig. 7) formedtherein to receive the clutch rollers 48 which operate between thesurfaces of the notches 4'! and the internal cylindrical surface of theclutch member 45 in the normal manner to prevent relative movement inone direction, while permitting a free relative movement in the oppositedirection.

' The fixed shaft 36 is supported in a portion Ha of the general housingH of the mechanism head, a key 49 (Fig. 5) being provided to preventrotation of the shaft 35, and a screw 50 passes through the closingguard cover LC and engages in the shaft 36 for drawing it toward andholding it in the left-hand position (Fig. 5) as determined by theengagement of the shoulder provided by its portion 58 with the axle raceof the bearing 34, which in turn engages against the structure Ha. Thefree end of the shaft 36 is provided with threads 5i for receiving anadjustment nut 52 which engages one of the pressure plates 53 whichdetermine the tension and operation of the spring 54.

The gear member 37 has a cylindrical surface 55 providing a plainbearing for the open end of the body 33, and also the aforesaid gearteeth 43, a surface 55 cooperative with the end surface of the body as afriction means for determining rotation of parts in one direction aswill be described hereinafter, and gear teeth 5? of pitch diameterlarger than the pitch diameter of gear teeth The axle races of bearings38 are spaced by a washer 58, and one pressure plate 53 operates tocause these bearings to engage against an internal shoulder 59 of gearmember 3'! and cause the friction surface 56 to bear forcibly againstthe end surface of the body 33. It will be noted that the body 33 has aninternal shoulder 68 which limits its leftward movement in Fig. 5, byengagement with the axle race of bearing 3 L The gear teeth 5? of gearmember 3? engage with a gear mounted on a bearing sleeve t3 and thusloosely rotatable about the axis of the pinion shaft 51 to which issecured the quill pinion 25 (Fig. 6). This shaft 6! has splines thereonfor receiving the clutch member 63 having a groove $9 for engagement bythe clutch fork lever Til for moving the clutch member 33 endwise. Inone position (Fig. 6) the clutch teeth H engage with corresponding teethon the gear 65. In a central position, the clutch member 68 is free ofany clutch engagement. In a righthand end position the clutch teeth '52are ongaged with similar teeth on a sleeve l3 which extends through theclosing guard plate RC (Fig. 6). Secured externally of the sleeve '53 isa collar '14. Extending from this collar "id is a rod 15. There is ananti-friction bearing E6 between the sleeve 13 and the guard plate RC.When the clutch teeth i2 are moved to the right (upon shifting of thecontrol lever ML as shown in Figure l for producing a movement of thesupport 19a of clutch lever 70, for ex ple) so as to engage the clutchteeth 13a on t e sleeve, then the shaft 67 is locked to the sleeve 73,and it may be turned manually. When, however, tl "e clutch teeth arereleased, then the shaft 52 r freely in the sleeve 73. This prev .1whereby the pinion shaft G'i may be it) the sleeve 73 or may be manuallyturned thr the aid of the sleeve 13. The shaft 81 is supported inanti-friction bearings l'i carried on peripheral flange extensions ofthe web wall HB of the housing H. The inner end of the pinion shaft 6'1has secured thereto a sprocket member '58 which is held in position by anut l9.

The weight of the spindle, gear and associated parts is counterbalancedby a large .s ht LW (Fig. 3) which may move upwardly and downwardly inthe hollow column C, connected to the balance chain BC which p es over aguide sprocket loose on the a driven sprocket 86, the sprocket i8, and ag. sprocket 8?, and is connected at its OLL 1 end to a small weight SWwhich ma' tains the chain tight. The proper proportionii g of theweights LW and SW permits accurate com ation of the weight of the parts.It is preferi d to have the weight LW sufhciently massive to accomplishan automatic gravitationally-produced raising of the spindle when itspower-effected downward feeding movement has been concluded.

The movement of the driven sprocket 88 is employed according to thepresent invention in determining the limits of upward and downwardmovement of the spindle. For this purpose as shown in Fig. 5, thesprocket 89 is pinned to a flange piece 95 which in turn is keyed to thereduced end of the shaft 95 and is held thereto by a nut 92. The shaft9! is journaled in a bushing supported in an internal web wall of thehousing H. A pin 94 connects the shaft 9! with a limit member 95 havinga radially projecting finger 56 whose path of movement causes it toencounter an inwardly extending lug 9"! located in a groove of a wormwheel $2. A second worm wheel 99 has a lug 586 which is presented in thepath of movement of a pin liii carried by the flange member 90. Thus, asthe sprocket 86 is driven, the flange member 92"; carries its pin l0!and the member 95 carries its finger 96 in rotational movement with theshaft 9| through a distance which is proportionate to the rotationalmovement of the gear pinion 25 and hence proportionate to the upward anddownward move ment of the spindle itself.

A worm Hi5 meshes with the worm wheel 98 (Figs. 2 and 5) and is fixed ona rotatable and endwise movable control shaft 66 (Fig. 4) by a pin NH.The shaft IE5 is supported by a sleeve tea which in turn is mounted forrotation and axial guiding in a web wall He of the housing H, and isprovided with a pin E09 engaged in an axial groove HS of the shaft N35.The sleeve S08 is also guided in an aperture H0 in the front wall of thehead H. The front end (at the right in Fig. 4) of the shaft 96 isprovided with a collar ill fixed thereto, and operating as an abutmentfor a coil spring H2 located within an annular space provided in thesleeve I 68, and abutting at its other end against this sleeve forproducing a relative leftward movement of the sleeve W8 and rightwardmovement of the shaft Hlein Fig. 4. The sleeve I08 extends through theaperture Ill! and is provided externally with a flange H3 having aconical peripheral surface which conforms to a similar surface providedon the split supporting ring H4 which is secured to the face of thehousing H by screws II5, so that the parts cooperate to prevent awithdrawal of the sleeve I68 from the housing H. A handle plate H6 witha handle lI'i is secured to the flange M3 by screws II8. The flange H3turns in the split ring H4, and the tightness of its fit may becontrolled by adjusting the closing screw I IQ of this split ring.

At its inner end (at the left in Fig. 4) a structure I25, providingspaced collars, is secured to shaft I563 by a pin I28. In Fig. 2, thesecollars receive between them the pins I2! of a crank lever 23 mounted ona pin I29 extending from the housing structure H, and provided with apivot connection I39 to a link arm I3I which extends downwardly into adash pot D which may be adjusted externally of the head. This dash potand its associated parts may, however, be omitted when the structuresare relatively light and the inertia effects are not great.

In similar manner, the worm wheel 99 is in mesh with a worm I35 securedby pin I38 on a shaft I31 which may rotate and move axially. This shaftI31 is supported in a sleeve I38 similar to sleeve I88 and having a pinI39 engaged in an axial groove Mi! of the shaft I31. The end of shaftI38 is provided with a collar I II forming an abutment for a coil springI42. The end of sleeve I38 projects through an aperture into the uprightfront face of the housing H and is provided externally of the housingwith a flange M3 which has a conical peripheral surface engaged by aconforming internal surface of an annular supporting plate I ls which issecured to the housing H. A handle plate I56 with a handle It? issecured to the flange its by screws Hi3. The rear end (at the left inFig. 4:) of shaft I3? is operatively connected with a limit switch RL.

The bifurcated clutch lever Ill (Figs. 2 and 6) is pivotally connectedat its upper end by a link I58 to a slide member IEI (Figs. 6 and 8)which is guided in the structure HI) and is pivotally connected at itsother end to a link I 52 extending from an arm 553 connected by pin I54to a rock shaft I55 carried by a structure I56 which is aligned by pinsI57 (Fig. 3) and secured by screws I58 within the housing H. An uppersleeve I59 rests upon structure IE6 and receives a screw ItIi whichengages a groove I6I in the upper end of shaft I55 to hold this shaftagainst downward movement, while permitting a free rocking thereof. Thepivot pin I62 which connects the link E52 with crank arm I53 alsoreceives a link I63 which connects it with the plunger I641 (Fig. 8) ofa solenoid ES. This solenoid is illustrated as of the type shown in thecopending application of Benjamin N. Foster, Serial No. 741,341, filedAugust 24, 1934, (now United States Patent No. 1,987,555). Whenenergized, the plunger let draws the arm I53 and link I52 into line sothat forces acting in the direction of slide member I5I do not effectany substantial movement. When de-energized, the return spring I 65operates to break the toggle and permit and assist the return movementof slide member I5I.

The circuit diagram in Figure 9 shows the connection of certainelectrical portions in the apparatus. As shown in Figure 1, theapparatus may be provided at the front of the mechanism head with Stopand Start push buttons, at a point where they are easily accessible tothe operator.

To start a cycle of movement, the operator depresses the Start pushbutton and this closes (Figure 9) a circuit from a main conductor 23%)through the Start button and conductor 292 to a winding of a controlrelay CR, and thus back to the other main conductor 2 M. As shown inFigure 3, the relay OR is preferably located within the mechanism headin close association with the other parts of the structure.

The energization of coil 283 causes the relay OR to close and therebyestablishes a maintaining circuit from conductor see by conductor 2514,the normally closed Stop button, conductor 2%, limit switch BL,conductor "296, bridge Zis'l of relay CR, and thence through the coil283 to the main conductor 233i. At the same time the relay CR sets up aninitiating circuit from main conductor 2% by conductor 2538, bridge 2B9,conductor 2 I d, the winding of solenoid ES and thus back to the mainconductor 28L This solenoid ES is energized and a cycle of movementbegins, comprising the downward stroke of the spindle 2I. At the limitof movement, as determined by the feed control system described herein,the limit switch BL is opened. The maintaining circuit throughconductors 2%, 285, 2% is interrupted and the relay CE. is de-energizedand moves to open position, resulting in a de-energization of thesolenoid ES so that this solenoid now operates to release the clutchconnection 'II and free the spindle shaft 61 from the feed drive. Thespindle it is returned by the gravity action of the weight LW to itsupper position and remains therein until the Start button is againdepressed. During the return movement of the spindle, the limit switchRL again closes.

It will be noted, however, that the operator has instantaneous controlover the apparatus as he may at any time depress the Stop button whichis in series with the limit switch RL and thus accomplish an immediatestoppage, in similar manner, of the downward feeding movement of thespindle 2 I, with a return of the spindle to its upward position againby the action of its counterweight LW.

In operation, the attendant releases the split rings I I4 and HM andmoves the handles II? and I- li until the desired adjustment of the stopfingers ii? and I96 is attained, for determining the upper and lowerlimits of travel of the spindle in its feeding movements. The rings I I4and 54 are then clamped again. The apparatus is thus adjusted to theparticular work at hand.

After positioning a piece of work in the usual way, the operatordepresses the Start button so that the solenoid ES attracts its core andbrings the arm I53 and link I52 into alignment with one another so thatthey thus operate to move slide member IIiI and rock the clutch lever Itso that the clutch elements 'II are engaged. The continuous rotation ofthe main feed shaft 3% causes the worm SI to rotate the worm wheel 32and therewith the body 33. During this initial phase of rapid forwardtraverse movement, the frictional engagement at surfaces 58 causes thebody 33 to rotate the gear body 37 at its own speed, this movement beingtransmitted through gear 35 and clutch elements ll and as and thus tothe quill shaft 61 and to the quill pinion 25, and thus the quill andspindle 2i are moved downwardly at a relatively rapid rate while thecounterweight LW is raised. The movement of the chain BC causes thesprocket 86 also to be rotated and therewith the shaft 9| with fingers96 and EM.

When the tool strikes the work and thus a greater resistance is opposedto the downward movement of the spindle 2i and the quill 24, the backpressure exerted through quill pinion 25, shaft gear E5 to the gearteeth 5? overcomes the frictional engagement at surface 56, so that thebody 33 overruns the gear body 37. This, however, causes a relativemovement of the pin 40 with respect to the gear body 37 and thus thedouble pinion tends to revolve upon its pin by traveling on gear teeth43, it. The turning movement, however, tends to cause a relativecounter-clockwise movement of the gear teeth 34 about their central axis(Figure '7 which is resisted by the rc-ilers ii). Thus the double pinionG2 is compelled to turn at a rate which is determined, for theparticular physical structures, by the speed of movement of the body 33and this movement is trans ;ted to gear teeth 53 and thus to the gearbody It will be understood that suitable numbers of teeth and pitchdiameters are employed for gears 53 and 44 and in double pinion :2,according to the relative speed to be attained during this siow workinfeed. Thus there may be thirty-two gear teeth &3, thirty-eight gearteeth 54, thirteen teeth on pinion in mesh with gear teeth and sixteenteeth on pinion 2-2 in mesh with gear teeth 55-, to give a ratio of28.44 to 1 between rapid traverse and slow working feed movements. Thecontinued upward movement of the gear body 3?, but at the lesser ratecontinues to produce a downward movement of the spindle 2i at aconsonantly lesser rate, and the tool is advanced into the work at thisrate.

This working feed continues until the finger ifil encounters the lug leton worm wheel 99 and causes a. rotation of the worm wheel 99. Thisrotation is transmitted to the screw I35 and causes a movement of therod 535 against the action of spring Hi2, and results in the opening ofthe limit switch RL, and thus determines the nature of the downwardmovement of the spindle M.

The solenoid is de-energized and the clutch elements ii are moved out ofengagement as deibed above, so that the shaft 6? is now fed from thepower drive from shaft 3! and is reti ned by its counterweight LW whichat the some time operates to move the shaft 9| backwardly. The limit ofthis backward movement is determined by the engagement of finger 98 withlug 91, causing a slight rotative movement of the worm wheel 98 which istransmitted to screw 26?: and absorbed by spring H2. As illus- :1, thisaction may be dampened by employ ne dash pot system 528-43! and dash potD.

The cessation of the resistance back through the gear train and gears6557 permits the frictional surface to operate again and thedifierential system including the body 33 and its parts then causes thegear body 3'1 to turn with an equiangular movement as before.

The sensitiveness of translation from the rapid forward traverse to theslow working feed is dete mined by the compression of spring 54 asadjusted by nut 52.

It is obvious that the invention is not limited solely to the form ofconstruction shown but that it may be modified in many ways within thescope of the appended claims.

Having thus described the invention, what I claim as new and desire tosecure by Letters Patent, is:

1. A device of the class described, comprising a frame, a member to beadvanced relative to said frame at varying predetermined speeds, a shafthaving an overrunning clutch surface and means for preventing retrogrademovement of the shaft relative to the frame, a differentiating geartrain including a body rotatable about said shaft and having aneccentric pivot, a first sun gear freely rotatable about said clutchsurface in one direction, a second sun gear connected with said member,and a double planet pinion on said pivot and meshing with said gears andoperative to produce a retrograde effect upon said first sun gearrelative to said shaft when said body moves relative to said second sungear, said second sun gear having friction means cooperative with saidbody for effecting a conjoint equiangular movement of the body, pinionand sun gears when the resistance to movement of said body is less thana predetermined value for producing a high advancing speed of saidmember, and clutch means cooperative with said clutch surface and saidfirst sun gear to prevent retrograde movement thereof by said planetpinion when the said resistance exceeds said predetermined value so thatthe differentiating train produces a slow advancing speed of said memher.

2. A device of the class described comprising a frame, a member to bemoved downward relative to the frame, counterbalance means for returningthe member upwardly, a shaft and means for preventing retrogrademovement of the shaft relative to the frame, a body moved in rotation, afirst sun gear freely rotatable in one direction about the shaft, asecond sun gear rotatable about the shaft, a double planet pinionpivoted on said body and in mesh with said gears and operative toproduce a retrograde movement of said first sun gear relative to saidsecond sun gear when said body moves relative to said second sun gear,said second sun gear having friction means cooperative with said bodyfor efiecting a conjoint equiangular movement of the body, pinion andsun gears when the resistance to downward movement of said member isless than a predetermined value, connecting means including a firstclutch for connecting said second sun gear for moving said memberdownwardly, and clutch means engaging the first sun gear and shaft toprevent retrograde movement of said first sun gear relative to saidshaft when the said resistance exceeds said value, said first clutchbeing effective in one position for connecting said second sun gear andmember for producing a downward movement of said member and when inanother position serving to interrupt said connection so that thecounterbalance means may return said member to its raised position.

3. A device of the class described, as in claim 2, including meansactuated by the member at a predetermined position of downward movementfor moving said clutch to the interrupting position.

4. A device of the class described, as in claim 2, including a circuitcloser, electromagnetic means for moving said clutch to connectingposition, and circuits connecting the closer and electromagnetic meansincluding means for maintaining the energization of the electromagnetduring the downward movement of said member, and means operated by saidmember at a predetermined position of downward movement for deenergizingsaid electromagnet so that said clutch will move to interruptingposition and said counterbalance means will return said member.

5. A device of the class described comprising a frame, a member to beadvanced relative to the frame at varying predetermined speeds, a shaftfixed to the frame, an element moving about the shaft continuously inthe same direction, a first gear journaled on the shaft for turningfreely with said element in a forward direction, meansforpreventingretrogrademotion of said first gear relative to the frame,a second gear journaled on the shaft, means including a clutch forconnecting said second gear to said member to produce advancement of thelatter, friction means for causing said element and second gear to turntogether when the resistance to advancing movement of said member isbelow a predetermined value, means cooperating with said element andsaid gears for producing a relative retrograde effort on said first sungear when said resistance exceeds said value and thereby operating foreffecting a slow continued advancing movement of said second gear andmember, and means operated at a predetermined point of advancement ofsaid member for disconnecting said clutch.

6. A device of the class described comprising a frame, a member to beadvanced relative to the frame at varying predetermined speeds, a shaftfixed to the frame, an element revolving about the shaft continuously inthe same direction and at substantially the same velocity, a first gearjournaled on the shaft to turn freely with said element, clutch means onthe shaft and first gear effective at all times for preventingretrograde movement of said first gear relative to said shaft, a secondgear connected for moving said member, constantly operating frictionmeans for causing said element and second gear to turn together at arapid rate when the resistance to movement of said member is below apredetermined value, and means cooperating with said element and saidgears for producing a relative retrograde effort on said first gear whensaid resistance exceeds said value and thereby cooperating with saidpreventing means for effecting a slow continued advancing movement ofsaid second gear and member.

'7. A device of the class described comprising a frame, a member to bemoved relative to the frame, a shaft fixed to the frame, an elementrevolving about the shaft continuously in the same direction and atsubstantially the same velocity, planet pinion means carried bodily inmovement with said element, a first sun gear in mesh therewith andfreely revcluble about the shaft in the direction of movement of saidelement, clutch means on the shaft and first gear for preventingretrograde movement of said first sun gear relative to the shaft, asecond sun gear having a lesser number of teeth than said first sun gearand in mesh with said planet pinion means and having constant frictionalengagement With said element to be turned at equiangular velocitytherewith when the resistance to movement of said second sun gear isless than a predetermined maximum, and means connecting said second sungear and member for advancing said member, said planet pinion meansoperating to produce a retrograde movement of said first sun gearrelative to said second sun gear when the resistance exceeds saidmaximum.

8. A device of the class described comprising a frame, a member to beadvanced relative to the frame, a shaft fixed to the frame, a revolubleelement providing a planetary body and means for driving the samerotation about the shaft, planet pi on means eccentrically mounted onsaid planetaly body, two sun gears each in mesh with said planet pinionmeans and each rotatable about the shaft, devices connecting said onesun gear with said member to advance the same, friction means forcausing said body to turn one said sun gear and devices and advance saidmember at a fast rate so long as the resistance to advancement of saidmember is below a predetermined maximum, said body, pinion means and sungears being constructed and arranged for producing a relative forwardmovement of the said one sun gear relative to the other said sun gearupon slippage of said friction means, and overrunning clutch means onthe other said sun gear and the shaft for preventing retrograde movementof said other sun gear relative to said shaft whereby to cause a slowrate of advancement of said member by said devices, said overrunningclutch means operating to permit movement of said other sun gear withthe planetary body during drive through said friction means.

EDWARD JOSLIN KINGSBURY.

